1. Field of Invention
The present invention relates generally to semiconductor processing equipment. More particularly, the present invention relates to a mechanism that enables the accuracy and bandwidth associated with a moving stage may be positioned to be improved.
2. Description of the Related Art
For precision instruments such as photolithography machines which are used in semiconductor processing, factors which affect the performance, e.g., accuracy, of the precision instrument generally must be dealt with and, insofar as possible, eliminated. When the performance of a precision instrument is adversely affected, as for example by pitching moments, products formed using the precision instrument may be improperly formed and, hence, function improperly. For instance, a photolithography machine which is subjected to pitching moments may cause an image projected by the photolithography machine to move, and, as a result, be aligned incorrectly on a projection surface such as a semiconductor wafer surface.
Scanning stages such as wafer scanning stages and reticle scanning stages are often used in semiconductor fabrication processes, and may be included in various photolithography and exposure apparatuses. Wafer scanning stages are generally used to position a semiconductor wafer such that portions of the wafer may be exposed as appropriate for masking or etching. Reticle scanning stages are generally used to accurately position a reticle or reticles for exposure over the semiconductor wafer. Patterns are generally resident on a reticle, which effectively serves as a mask or a negative for a wafer. When a reticle is positioned over a wafer as desired, a beam of light or a relatively broad beam of electrons may be collimated through a reduction lens, and provided to the reticle on which a thin metal pattern is placed. Portions of a light beam, for example, may be absorbed by the reticle while other portions pass through the reticle and are focused onto the wafer.
Stages, e.g., either a wafer positioning stage or a reticle positioning stage, are often required to be relatively high accuracy stages, since the positioning of wafers and reticles is critical in ensuring that beams may be properly focused onto the wafer. For example, in order to ensure that a reticle may be properly positioned, it is typically desirable for a reticle positioning stage to be a high precision stage.
Therefore, what is needed is a method and an apparatus for improving the accuracy with which a moving stage may be positioned. That is, what is desired is a system and a method for increasing the bandwidth and the precision associated with positioning a moving stage of an overall stage apparatus without significantly increasing the mass of the overall stage apparatus.